Indonesia is one of the most seismically active countries in the world, and its large, vulnerable population makes reliable seismic hazard assessment an urgent priority. In 2016, the Indonesian Ministry of Public Works and Housing established a team of earthquake scientists and engineers tasked with improving the input data available for revising the national seismic hazard map. They compiled results of recent active fault studies using geological, geophysical, and geodetic observations, as well as a new comprehensive earthquake catalog including hypocenters relocated in a three-dimensional velocity model. Seismic hazard analysis was undertaken using recently developed ground motion prediction equations (GMPEs), and logic trees for the inclusion of epistemic uncertainty associated with different choices for GMPEs and earthquake recurrence models. The new seismic hazard maps establish the importance of active faults and intraslab seismicity, as well as the subduction megathrust, in determining the level of seismic hazard, especially in onshore, populated areas. The new Indonesian hazard maps will be used to update national standards for design of earthquake-resilient buildings and infrastructure.

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Abstract. In 2010 a national team (Team 9) developed the hazard curve and maximum considered earthquake (MCE) for the whole Indonesian area. The results were further applied in this study. Risk-targeted ground motions (RTGM) with 1% probability of building collapse in 50 years were developed by integrating the hazard curve with the structural capacity distribution. Parametric study on various variables that affect the log-normal standard deviation suggests a value of 0.7. In the effort to obtain the RTGM for the whole Indonesian region, integration was carried out using definite integration in which the curves are split into thin vertical strips and the areas below each curve are multiplied and summed. Detailed procedures and verification are given in this paper. An example of RTGM calculation was carried out for Jakarta City and then applied to the whole Indonesian region. Risk coefficients defining the ratio between RTGM and MCE were eventually developed and mapped. Risk coefficient development was generated for two periods of interest, i.e. a short time period (T = 0.2 seconds) and a 1-second period, respectively. Based on the results, for the period of 1.0 seconds 55% of Indonesian cities/districts have a risk coefficient in the range of 0.9 to 1.1 and about 37% in the range of 0.7 to 0.9, with only 5% in the range of 1.1 to 1.25.

Abstract.A nationwide Vs 30 map for Indonesia was developed based on automated topographic classification from 90-m grid digital elevation data and their correlation with Vs 30 . Automated topographic classification has been proposed by Iwahashi and Pike (2007) and a procedure to convert topographic class into Vs 30 maps has been developed by Imamura and Furuta (2015) based on Vs data from J-SHIS (Japan Seismic Hazard Information System). In order to be suitable for Indonesia, calibration work according to Imamura and Furuta's procedure should be conducted since the geotechnical conditions in Japan may not be the same as in Indonesia. This paper presents adjustment of the Vs 30 correlation by Imamura and Furuta to convert topographic class into Vs 30 and construct a Vs 30 map of Indonesia. This correlation was calibrated by using Vs data from BMKG (Indonesian Agency for Meteorological, Climatological, and Geophysics) as well as standard penetration test logs that were collected by the authors. Utilization of local field measurement data will certainly enhance the reliability of the Vs 30 map. The developed nationwide Vs 30 map will be very useful for disaster mitigation programs and for preliminary design of earthquake resistant buildings and infrastructure in Indonesia.

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This study is performed to develop spectral hazard map for Indonesia with a Return Period of 2500 years earthquake. It will be proposed for revision of the Indonesian hazard map in SNI-03-1726-2002 as response to the meeting organized by the Department of Public Works on 27-October-2008 in Jakarta. The meeting has decided to revise the Indonesia hazard map by referring to IBC-2006 where spectral acceleration values at Peak Ground Acceleration/PGA, 0.2 and 1.0 second with a return period of 2500 year will be applied for general buildings. The spectral hazard map was analyzed using total probability method and three dimensional (3-D) source models with recent seismotectonic parameters. Four source models were used in this analysis, namely: shallow background, deep background, fault, and subduction source models. Generally, the results of analysis show the values of PGA with a return period of 2500 years relatively higher 1.2-3.0 times than in SNI-03-1726-2002.